Polishing bonnet



May 9, 1950 F. LIVINGSTON 2,507,412 POLISHING- BONNET Filed Feb. 13.l 194s Patented May 9, 1950 UNITED STATES PATENT OFFICE POLISHING BONNET Frank Livingston, Worcester, Mass.

. Application February 13, 1948, Serial No. 8,110

5 Claims.

The present invention relates to polishing and bufng devices, and more particularly to a polishing or bung bonnet which is adapted to be removably secured over a rotatable disk of a portable power tool of the type which is commonly employed in the polishing of a variety of articles, such as, for example, furniture and automobile bodies.

The mostl common type of polishing bonnet employed in the past, and at the present time, comprises a circular-shaped piece of flexible sheepskin or pile fabric which has secured about its peripheral edge a border of plain cloth provided with a draw string. To use such a bonnet or pad, it is positioned over one face of the rotatable disk of a power tool with the hair or pile side of the bonnet exposed. Thereafter, the draw string is tightened and its ends secured together so that the cloth border is drawn about the periphery of the disk thereby to hold the bonnet on the disk. After the power 1tool is made active, the disk will rotate and carry with it the pad or bonnet which thereafter may be applied to a surface to be polished.

Although literally thousands of the above noted type of polishing bonnets are employed every day in this country in automobile garages, body shops,

and furniture plants, theY fact is that such a bonnet has a serious drawback in that it has no means whatsoever for either initially centering it upon the tool disk or maintaining it in such a central position in the event that .an operator could initially center the same. In this latter connection, it should be realized that in actual use, such a bonnet is rotated by the power tool, and asthe rotating bonnet is applied to asurface to be polished, the operator slides the bonnet back and forth over the surface, with the result that the bonnet will tend to shift relative to the tool disk and thus become eccentric with the disk axis, even though the operator was successful in initially centering the bonnet upon the disk.

With the bonnet disposed eccentrically of the disk, the latter element will be in a state of unbalance, thus causing the entire power tool to vibrate when in use. Since such tools are geared to drive the disk and bonnet at about 1400 R. P. M., this vibration becomes very objectionable to an operator, and, in fact, causes operator fatigue.

It is also to be understood that the degree of eccentricity between disk and bonnet many times is so great that a portion of the disk periphery is no longer covered by the sheepskin, but only by the cloth border material and thus, whenever such an exposed portion of the border material engages the surface to be polished, it will be out, with the result that the surface is marred and the bonnet is rendered completely worthless. In this connection, it is to be appreciated that n0 sheepskin, or other appropriate bonnet material, is flexible enough to permit its marginal portion to be properly and completely folded about a disk periphery. It is for this reason that a border of plain cloth is employed about the periphery of the bonnet material. Therefore, since it is inevitable that the tool disk will cut the bonnet border, the above described conventional type of bonnet is short-lived. Furthermore, since an operator cannot, with impunity, bring the edge portion of the shifted bonnet against an article to be polished, the use of the bonnet is restricted, for much polishing Work is required at the juncture of angled surfaces.

In an attempt to rectify the above noted sh0rtcomings, it has become standard practice in many shops to cut a center hole in the bonnet so that the bonnet may be actually clamped upon the tool disk by the disk nut. In other words, the operators rst remove the nut which retains the disk upon the tool, and then they apply the bonnet over the disk so that the bonnet hole will receive the shaft upon which the disk is mounted. Thereafter, the nut is threaded over the shaft so as to clamp both the bonnet and disk in position on the tool. With this arrangement, the bonnet is prevented from shifting relative to the disk. However, as soon as the bonnet pile wears, or in the event that excessive pressure is applied to the tool and bonnet, the nut will dig into the work so as to spoil the same. With such an arrangement, the operator can only safely apply less than one half of the bonnet surface to the vwork to be polished and thus, the time for polishing a surface is greatly increased. Furthermore, the time consumed by an operator in an veffort to socenter these conventional bonnets upon a disk is appreciable, and thus, costly.

It is, therefore, a primary object of the present invention to provide a polishing bonnet of the 'flexible type which is so constructed that it will structed that it will automatically center itself with respect to a tool disk upon being applied thereto, and remain so centered during the operation of the tool.

With the above and other objects in View, as will hereinafter appear, the invention comprises the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention from which the several features of the invention and the advantages attained thereby will be readily understood by` those skilled in the art.

The several features of the present invention will be clearly understood from the following dep scription and accompanying drawings in which,

Fig. l represents a perspective view of a power tool to which the present invention is applied.

Fig. 2 represents, on an enlarged scale, a sectional view taken substantially along the line 2^2 of Fig. l.

Fig. 3 represents, on an enlarged scale, a portion of the device disclosed in Fig. 2.

Fig. 4. represents, on a scale similar to that employed in Fig. l, the present invention with the draw strings thereof loosened.

Fig. 5 represents a perspective view of a rotatable disk which is adapted to be secured directly to the power tool illustrated in Fig. 1.

Referring particularly to Fig. l, there is disclosed a common type power tool comprising a motor casing l upon the forward portion of which is mounted a combined gear casing and handle member Il. Projecting downwardly from the gear casing il is the usual rotatable shaft i2 to which a polishing padmay be applied in a manner as will be hereinafter described. The shaft l2 is `driven in the usual manner from an electric motor which is contained Iwithin the casi ing l0. end portion with a handle member I3 which carries a suitable switch I4 by which the motor circuit may be controlled. The circuit wires may be led to the motor through a cable I5v which is shown as extending through the handle I3, all in the usual manner.

Referring to Figs. 1 and 2, the rotatable shaft I2 may be provided at its lower end portion with a flange i6 and a threaded end portion I1 over which a fiber disk i8 may be mounted. A nut I9 may be threaded upon the shaft portion i1 for the purpose of securing the disk I2 rigidly upon the shaft l2. Thus, the disk -IB will rotate with the shaft i2, all in the usual manner.

is hereinabove set forth, it has been the usual practice to secure a polishing bonnet or pad over one face of the disk t8, but diiiculties were encountered due to the fact that such prior type polishing bonnets had a tendency to shift relative to the disk I8 thereby becoming eccentric with the axis of the shaft i2. The present invention completely obviates this difculty.

Referring now to Figs. 2, 3 and 4, a preferred form of the present invention comprises a circular piece of sheepskin 2liv having wool or hair fibers 2i projecting from one face portion thereof. Secured to the peripheral portion of the sheepskin or base member 2Q is a circular piece of border material 22. Referring particularly to Fig. 3, it is to be understood that in a preferred form of the presen-t invention the border material 22 is folded upon itself and the juxtaposed edge portions 23, 23 thereof are secured directly to the peripheral edge portion 24 of the sheepskin or base member by means of over-edge The casing Hi is provided at its other stitches 25. By thus securing the free edge portions of the border material to the circularshaped peripheral edge portion 24 of the sheepskin 20, the border material will be formed as a circular strip, as best disclosed in Fig. 4. The end portions 26, 26 of this border strip 'are left free so that a draw string 21 may be inserted within the confines thereof. Thus, the pad or bonnet may be applied to the free face of a disk I 8 and the border material may be drawn over the peripheral edge portion of the disk by means of the draw string 21. By securing the free end portions of the draw string 21 together in the form of 4a bow 28, 'as best illustrated in Fig. l, the bonnet nay be held in place upon the disk I8. However, as hereinabove described, it should be understood that it would be almost impossible for an operator to place such a bonnet exactly centrally on the disk i8, and even if it were -located in a central position, the fact remains that the bonnet or pad. wouid shift radially of the disk I8 during its rotation, with the result that the sheepskin or base 29' would be positioned eccentrically of the disk. With such an eccentric condition. prevailing, the edge portions of any pad or bonnet, constructed in the conventional manner as thus far described, would have a tendency to dig into a polished surface, thereby marring the same.. In order to obviate this shifting to eccentric position, the pad or bonnet of my invention is provided with a relatively stiff binding tape 29. Referring particularly to Figs. 3 and 4, it is to be understood that the binding tape 29 is applied about the juxtaposed edge portions 23 and 2li of the border material and sheepskin 2i). This binding tape may be secured to these edge portions by means of a row of stitches 31], and by properly drawing the end portions 3i, 3l of the tape together during thisV stitching operation, it wil-1 be understood that the tape will form an annular ring or ridge of material which will project substantially at Fright angles to the plane of the base material 20.

With the binding tape so applied to the bonnet, it is to be understood that when the bonnet is positioned over the disk I8 in a manner as particularly disclosed in Fig. 2, the tape will function to positionthe entire bonnet concentrically with the disk I8 and the shaft l2. Thereafter, when the draw string 2l has its ends tightened and secured together, the border material will of necessity be drawn tightly over the binding tape 2Q and the periphery of the disk i8 to the end that the outer portions of the tape will be more or less drawnrover the periphery of the disk so as effectively to secure the bonnet in its proper position.. A polishing bonnet so constructed mair be readily applied to` a rotatable tool disk and, furthermore, suchga bonnet when once properly secured to the disk can never shift so as to be positioned eccentrically of the disk and shaft.

Therefore, the present invention obviates completely the above noted shortcomings that were inherent in those `bonnets of the flexible type which have been employed heretofore. It should be also understood that the present vinvention may be incorporated in any type of bonnet whether the same utilizes a sheepskin or any other type of appropriate base material. Those skilled in the art will further appreciate that the present invention provides a polishing bonnet which is not only efficient in use, but which at the same time is most inexpensive of manufacture.

I claim: l Y l 1. A polishing bonnet for a tool having a rotatable shaft and a disk secured upon an end portion of the shaft, comprising, a substantially fiat circular polishing pad adapted to be positioned over one face of the disk, means in the form of an annular ring formed at the peripheral edge portion of said pad and projecting substantially at right angles from one face of said pad so as to encircle the disk periphery, a strip of border material formed about the peripheral edge portion of said pad at the base of said annular ring and adapted to be drawn over said annular ring and the peripheral edge of said disk, and means associated with said border strip for securing the same about the disk periphery thereby to maintain said pad in concentric position upon the disk.

2. A polishing bonnet for a tool having a rotatable shaft and a disk secured upon an end portion of the shaft, comprising, a at circular polishng pad of flexible material adapted to be positioned over one face of the disk, means in the form of a relatively stiff annular ring formed at the peripheral edge portion of said pad and projecting substantially at right angles from one face of said pad so as snugly to encircle the disk periphery, a circular strip of border material formed about the peripheral edge portion of said pad at the base of said annular ring, and a draw string attached to said border strip for drawing the free edge portion of the latter about the disk periphery and about said annular ring thereby to maintain said pad in position upon the disk.

3. An article of the class described, comprising, a polishing pad, a strip of border material disposed against the peripheral edge portion of said pad with one edge portion of said border strip being in juxtaposition with the peripheral edge portion of said pad, a binding tape disposed and stitched about the juxtaposed edges of said pad and border strip and having the both end portions of said tape drawn and secured together so that said tape and said juxtaposed pad and strip edges will project substantially at right angles to one face of said pad, and means associated with said strip for drawing the free edge portion thereof over the periphery of said pad and about said binding tape.

4. An article of the class described, comprising, a iiat circular polishing pad of flexible material, an elongated strip of border material folded lengthwise of itself with its longitudinal edge portions in juxtaposed relation and positioned in juxtaposition with the peripheral edge portion of said pad, a line of stitches securing the edge portions of said strip to that of said pad, a binding tape disposed and stitched about the circular juxtaposed edges of said pad and border strip and having the both end portions of said tape drawn and secured together so that said tape and said juxtapoed pad and strip edges form an annular ring which projects substantially at right angles from one face of said pad, and a draw string positioned Within the interior of said folded strip for drawing the free folded edge portion of said strip over the periphery of said pad and about said binding tape.

5. A polishing bonnet for a tool having a rotatable shaft and a disk secured upon an end portion of the shaft, comprising, a circular polishing pad of flexible material for positioning over one face of the disk, said pad having a substantially flat face portion and a peripheral edge portion, means in the form of a stiff annular ring secured at the peripheral edge portion of said pad and projecting substantially at right angles from the face of said pad so as snugly to encircle the disk periphery, a circular strip of exible border material secured to said ring, and means carried by said strip of border material for drawing the free edge of the latter over the exposed peripheral edge portion of said disk.

FRANK LIVINGSTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,470,014 Kootz et al Oct. 9, 1923 1,757,228 Albertson et al May 6, 1930 

